/***********************************************************************

	This file is part of KEEL-software, the Data Mining tool for regression, 
	classification, clustering, pattern mining and so on.

	Copyright (C) 2004-2010
	
	F. Herrera (herrera@decsai.ugr.es)
    L. Sánchez (luciano@uniovi.es)
    J. Alcalá-Fdez (jalcala@decsai.ugr.es)
    S. García (sglopez@ujaen.es)
    A. Fernández (alberto.fernandez@ujaen.es)
    J. Luengo (julianlm@decsai.ugr.es)

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see http://www.gnu.org/licenses/
  
**********************************************************************/

/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    Instance.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */

package keel.Algorithms.SVM.SMO.core;

import java.io.Serializable;
import java.util.Enumeration;

import keel.Dataset.Attribute;
import keel.Dataset.Attributes;

/**
 * Class for handling an instance. All values (numeric, date, nominal, string
 * or relational) are internally stored as floating-point numbers. If an
 * attribute is nominal (or a string or relational), the stored value is the
 * index of the corresponding nominal (or string or relational) value in the
 * attribute's definition. We have chosen this approach in favor of a more
 * elegant object-oriented approach because it is much faster. <p>
 *
 * Typical usage (code from the main() method of this class): <p>
 *
 * <code>
 * ... <br>
 *      
 * // Create empty instance with three attribute values <br>
 * Instance inst = new Instance(3); <br><br>
 *     
 * // Set instance's values for the attributes "length", "weight", and "position"<br>
 * inst.setValue(length, 5.3); <br>
 * inst.setValue(weight, 300); <br>
 * inst.setValue(position, "first"); <br><br>
 *   
 * // Set instance's dataset to be the dataset "race" <br>
 * inst.setDataset(race); <br><br>
 *   
 * // Print the instance <br>
 * System.out.println("The instance: " + inst); <br>
 *
 * ... <br>
 * </code><p>
 *
 * All methods that change an instance are safe, ie. a change of an
 * instance does not affect any other instances. All methods that
 * change an instance's attribute values clone the attribute value
 * vector before it is changed. If your application heavily modifies
 * instance values, it may be faster to create a new instance from scratch.
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 1.1 $ 
 */
public class Instance
implements Serializable {

	/** for serialization */
	static final long serialVersionUID = 1482635194499365122L;

	/** Constant representing a missing value. */
	protected static final double MISSING_VALUE = Double.NaN;

	/** 
	 * The dataset the instance has access to.  Null if the instance
	 * doesn't have access to any dataset.  Only if an instance has
	 * access to a dataset, it knows about the actual attribute types.  
	 */
	protected /*@spec_public@*/ Instances m_Dataset;

	/** The instance's attribute values. */
	protected /*@spec_public non_null@*/ double[] m_AttValues;

	/** The instance's weight. */
	protected double m_Weight;

	/**
	 * Constructor that copies the attribute values and the weight from
	 * the given instance. Reference to the dataset is set to null.
	 * (ie. the instance doesn't have access to information about the
	 * attribute types)
	 *
	 * @param instance the instance from which the attribute
	 * values and the weight are to be copied 
	 */
	//@ ensures m_Dataset == null;
	public Instance(/*@non_null@*/ Instance instance) {

		m_AttValues = instance.m_AttValues;
		m_Weight = instance.m_Weight;
		m_Dataset = null;
	}

	/**
	 * Constructor that inititalizes instance variable with given
	 * values. Reference to the dataset is set to null. (ie. the instance
	 * doesn't have access to information about the attribute types)
	 *
	 * @param weight the instance's weight
	 * @param attValues a vector of attribute values 
	 */
	//@ ensures m_Dataset == null;
	public Instance(double weight,  /*@non_null@*/ double[]attValues){

		m_AttValues = attValues;
		m_Weight = weight;
		m_Dataset = null;
	}

	/**
	 * Constructor of an instance that sets weight to one, all values to
	 * be missing, and the reference to the dataset to null. (ie. the instance
	 * doesn't have access to information about the attribute types)
	 *
	 * @param numAttributes the size of the instance 
	 */
	//@ requires numAttributes > 0;    // Or maybe == 0 is okay too?
	//@ ensures m_Dataset == null;
	public Instance(int numAttributes) {

		m_AttValues = new double[numAttributes];
		for (int i = 0; i < m_AttValues.length; i++) {
			m_AttValues[i] = MISSING_VALUE;
		}
		m_Weight = 1;
		m_Dataset = null;
	}

	/**
	 * Returns the attribute with the given index.
	 *
	 * @param index the attribute's index
	 * @return the attribute at the given position
	 * @throws UnassignedDatasetException if instance doesn't have access to a
	 * dataset
	 */ 
	//@ requires m_Dataset != null;
	public /*@pure@*/ Attribute attribute(int index) {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return Attributes.getAttribute(index);
	}

	/**
	 * Returns the attribute with the given index. Does the same
	 * thing as attribute().
	 *
	 * @param indexOfIndex the index of the attribute's index 
	 * @return the attribute at the given position
	 * @throws UnassignedDatasetException if instance doesn't have access to a
	 * dataset
	 */ 
	//@ requires m_Dataset != null;
	public /*@pure@*/ Attribute attributeSparse(int indexOfIndex) {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.attribute(indexOfIndex);
	}

	/**
	 * Returns class attribute.
	 *
	 * @return the class attribute
	 * @throws UnassignedDatasetException if the class is not set or the
	 * instance doesn't have access to a dataset
	 */
	//@ requires m_Dataset != null;
	public /*@pure@*/ Attribute classAttribute() {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.classAttribute();
	}

	/**
	 * Returns the class attribute's index.
	 *
	 * @return the class index as an integer 
	 * @throws UnassignedDatasetException if instance doesn't have access to a dataset 
	 */
	//@ requires m_Dataset != null;
	//@ ensures  \result == m_Dataset.classIndex();
	public /*@pure@*/ int classIndex() {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.classIndex();
	}

	/**
	 * Tests if an instance's class is missing.
	 *
	 * @return true if the instance's class is missing
	 * @throws UnassignedClassException if the class is not set or the instance doesn't
	 * have access to a dataset
	 */
	//@ requires classIndex() >= 0;
	public /*@pure@*/ boolean classIsMissing() {

		if (classIndex() < 0) {
			throw new UnassignedClassException("Class is not set!");
		}
		return isMissing(classIndex());
	}

	/**
	 * Returns an instance's class value in internal format. (ie. as a
	 * floating-point number)
	 *
	 * @return the corresponding value as a double (If the 
	 * corresponding attribute is nominal (or a string) then it returns the 
	 * value's index as a double).
	 * @throws UnassignedClassException if the class is not set or the instance doesn't
	 * have access to a dataset 
	 */
	//@ requires classIndex() >= 0;
	public /*@pure@*/ double classValue() {

		if (classIndex() < 0) {
			throw new UnassignedClassException("Class is not set!");
		}
		return value(classIndex());
	}

	/**
	 * Produces a shallow copy of this instance. The copy has
	 * access to the same dataset. (if you want to make a copy
	 * that doesn't have access to the dataset, use 
	 * <code>new Instance(instance)</code>
	 *
	 * @return the shallow copy
	 */
	//@ also ensures \result != null;
	//@ also ensures \result instanceof Instance;
	//@ also ensures ((Instance)\result).m_Dataset == m_Dataset;
	public /*@pure@*/ Object copy() {

		Instance result = new Instance(this);
		result.m_Dataset = m_Dataset;
		return result;
	}

	/**
	 * Returns the dataset this instance has access to. (ie. obtains
	 * information about attribute types from) Null if the instance
	 * doesn't have access to a dataset.
	 *
	 * @return the dataset the instance has accesss to
	 */
	//@ ensures \result == m_Dataset;
	public /*@pure@*/ Instances dataset() {

		return m_Dataset;
	}

	/**
	 * Deletes an attribute at the given position (0 to 
	 * numAttributes() - 1). Only succeeds if the instance does not
	 * have access to any dataset because otherwise inconsistencies
	 * could be introduced.
	 *
	 * @param position the attribute's position
	 * @throws RuntimeException if the instance has access to a
	 * dataset 
	 */
	//@ requires m_Dataset != null;
	public void deleteAttributeAt(int position) {

		if (m_Dataset != null) {
			throw new RuntimeException("Instance has access to a dataset!");
		}
		forceDeleteAttributeAt(position);
	}

	/**
	 * Returns an enumeration of all the attributes.
	 *
	 * @return enumeration of all the attributes
	 * @throws UnassignedDatasetException if the instance doesn't
	 * have access to a dataset 
	 */
	//@ requires m_Dataset != null;
	public /*@pure@*/ Enumeration enumerateAttributes() {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.enumerateAttributes();
	}

	/**
	 * Tests if the headers of two instances are equivalent.
	 *
	 * @param inst another instance
	 * @return true if the header of the given instance is 
	 * equivalent to this instance's header
	 * @throws UnassignedDatasetException if instance doesn't have access to any
	 * dataset
	 */
	//@ requires m_Dataset != null;
	public /*@pure@*/ boolean equalHeaders(Instance inst) {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.equalHeaders(inst.m_Dataset);
	}

	/**
	 * Tests whether an instance has a missing value. Skips the class attribute if set.
	 * @return true if instance has a missing value.
	 * @throws UnassignedDatasetException if instance doesn't have access to any
	 * dataset
	 */
	//@ requires m_Dataset != null;
	public /*@pure@*/ boolean hasMissingValue() {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		for (int i = 0; i < numAttributes(); i++) {
			if (i != classIndex()) {
				if (isMissing(i)) {
					return true;
				}
			}
		}
		return false;
	}

	/**
	 * Returns the index of the attribute stored at the given position.
	 * Just returns the given value.
	 *
	 * @param position the position 
	 * @return the index of the attribute stored at the given position
	 */
	public /*@pure@*/ int index(int position) {

		return position;
	}

	/**
	 * Inserts an attribute at the given position (0 to 
	 * numAttributes()). Only succeeds if the instance does not
	 * have access to any dataset because otherwise inconsistencies
	 * could be introduced.
	 *
	 * @param position the attribute's position
	 * @throws RuntimeException if the instance has accesss to a
	 * dataset
	 * @throws IllegalArgumentException if the position is out of range
	 */
	//@ requires m_Dataset == null;
	//@ requires 0 <= position && position <= numAttributes();
	public void insertAttributeAt(int position) {

		if (m_Dataset != null) {
			throw new RuntimeException("Instance has accesss to a dataset!");
		}
		if ((position < 0) ||
				(position > numAttributes())) {
			throw new IllegalArgumentException("Can't insert attribute: index out "+
			"of range");
		}
		forceInsertAttributeAt(position);
	}

	/**
	 * Tests if a specific value is "missing".
	 *
	 * @param attIndex the attribute's index
	 * @return true if the value is "missing"
	 */
	public /*@pure@*/ boolean isMissing(int attIndex) {

		if (Double.isNaN(m_AttValues[attIndex])) {
			return true;
		}
		return false;
	}

	/**
	 * Tests if a specific value is "missing". Does
	 * the same thing as isMissing() if applied to an Instance.
	 *
	 * @param indexOfIndex the index of the attribute's index 
	 * @return true if the value is "missing"
	 */
	public /*@pure@*/ boolean isMissingSparse(int indexOfIndex) {

		if (Double.isNaN(m_AttValues[indexOfIndex])) {
			return true;
		}
		return false;
	}

	/**
	 * Tests if a specific value is "missing".
	 * The given attribute has to belong to a dataset.
	 *
	 * @param att the attribute
	 * @return true if the value is "missing"
	 */
	public /*@pure@*/ boolean isMissing(Attribute att) {
		int index;
		index = -1;
		for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
			if(att == Attributes.getAttribute(index))
				index = i;
		return isMissing(index);
	}

	/**
	 * Tests if the given value codes "missing".
	 *
	 * @param val the value to be tested
	 * @return true if val codes "missing"
	 */
	public static /*@pure@*/ boolean isMissingValue(double val) {

		return Double.isNaN(val);
	}

	/**
	 * Merges this instance with the given instance and returns
	 * the result. Dataset is set to null.
	 *
	 * @param inst the instance to be merged with this one
	 * @return the merged instances
	 */
	public Instance mergeInstance(Instance inst) {

		int m = 0;
		double [] newVals = new double[numAttributes() + inst.numAttributes()];
		for (int j = 0; j < numAttributes(); j++, m++) {
			newVals[m] = value(j);
		}
		for (int j = 0; j < inst.numAttributes(); j++, m++) {
			newVals[m] = inst.value(j);
		}
		return new Instance(1.0, newVals);
	}

	/**
	 * Returns the double that codes "missing".
	 *
	 * @return the double that codes "missing"
	 */
	public /*@pure@*/ static double missingValue() {

		return MISSING_VALUE;
	}

	/**
	 * Returns the number of attributes.
	 *
	 * @return the number of attributes as an integer
	 */
	//@ ensures \result == m_AttValues.length;
	public /*@pure@*/ int numAttributes() {

		return m_AttValues.length;
	}

	/**
	 * Returns the number of class labels.
	 *
	 * @return the number of class labels as an integer if the 
	 * class attribute is nominal, 1 otherwise.
	 * @throws UnassignedDatasetException if instance doesn't have access to any
	 * dataset
	 */
	//@ requires m_Dataset != null;
	public /*@pure@*/ int numClasses() {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		return m_Dataset.numClasses();
	}

	/**
	 * Returns the number of values present. Always the same as numAttributes().
	 *
	 * @return the number of values
	 */
	//@ ensures \result == m_AttValues.length;
	public /*@pure@*/ int numValues() {

		return m_AttValues.length;
	}

	/** 
	 * Replaces all missing values in the instance with the
	 * values contained in the given array. A deep copy of
	 * the vector of attribute values is performed before the
	 * values are replaced.
	 *
	 * @param array containing the means and modes
	 * @throws IllegalArgumentException if numbers of attributes are unequal
	 */
	public void replaceMissingValues(double[] array) {

		if ((array == null) || 
				(array.length != m_AttValues.length)) {
			throw new IllegalArgumentException("Unequal number of attributes!");
		}
		freshAttributeVector();
		for (int i = 0; i < m_AttValues.length; i++) {
			if (isMissing(i)) {
				m_AttValues[i] = array[i];
			}
		}
	}

	/**
	 * Sets the class value of an instance to be "missing". A deep copy of
	 * the vector of attribute values is performed before the
	 * value is set to be missing.
	 *
	 * @throws UnassignedClassException if the class is not set
	 * @throws UnassignedDatasetException if the instance doesn't
	 * have access to a dataset
	 */
	//@ requires classIndex() >= 0;
	public void setClassMissing() {

		if (classIndex() < 0) {
			throw new UnassignedClassException("Class is not set!");
		}
		setMissing(classIndex());
	}

	/**
	 * Sets the class value of an instance to the given value (internal
	 * floating-point format).  A deep copy of the vector of attribute
	 * values is performed before the value is set.
	 *
	 * @param value the new attribute value (If the corresponding
	 * attribute is nominal (or a string) then this is the new value's
	 * index as a double).  
	 * @throws UnassignedClassException if the class is not set or if the instance doesn't
	 * have access to a dataset 
	 */
	//@ requires classIndex() >= 0;
	public void setClassValue(double value) {

		if (classIndex() < 0) {
			throw new UnassignedClassException("Class is not set!");
		}
		setValue(classIndex(), value);
	}

	/**
	 * Sets the class value of an instance to the given value. A deep
	 * copy of the vector of attribute values is performed before the
	 * value is set.
	 *
	 * @param value the new class value (If the class
	 * is a string attribute and the value can't be found,
	 * the value is added to the attribute).
	 * @throws UnassignedClassException if the class is not set
	 * @throws UnassignedDatasetException if the dataset is not set
	 * @throws IllegalArgumentException if the attribute is not
	 * nominal or a string, or the value couldn't be found for a nominal
	 * attribute 
	 */
	//@ requires classIndex() >= 0;
	public final void setClassValue(String value) {

		if (classIndex() < 0) {
			throw new UnassignedClassException("Class is not set!");
		}
		setValue(classIndex(), value);
	}

	/**
	 * Sets the reference to the dataset. Does not check if the instance
	 * is compatible with the dataset. Note: the dataset does not know
	 * about this instance. If the structure of the dataset's header
	 * gets changed, this instance will not be adjusted automatically.
	 *
	 * @param instances the reference to the dataset 
	 */
	public final void setDataset(Instances instances) {

		m_Dataset = instances;
	}

	/**
	 * Sets a specific value to be "missing". Performs a deep copy
	 * of the vector of attribute values before the value is set to
	 * be missing.
	 *
	 * @param attIndex the attribute's index
	 */
	public final void setMissing(int attIndex) {

		setValue(attIndex, MISSING_VALUE);
	}

	/**
	 * Sets a specific value to be "missing". Performs a deep copy
	 * of the vector of attribute values before the value is set to
	 * be missing. The given attribute has to belong to a dataset.
	 *
	 * @param att the attribute
	 */
	public final void setMissing(Attribute att) {
		int index;
		index = -1;
		for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
			if(att == Attributes.getAttribute(index))
				index = i;
		setMissing(index);
	}

	/**
	 * Sets a specific value in the instance to the given value 
	 * (internal floating-point format). Performs a deep copy
	 * of the vector of attribute values before the value is set.
	 *
	 * @param attIndex the attribute's index 
	 * @param value the new attribute value (If the corresponding
	 * attribute is nominal (or a string) then this is the new value's
	 * index as a double).  
	 */
	public void setValue(int attIndex, double value) {

		freshAttributeVector();
		m_AttValues[attIndex] = value;
	}

	/**
	 * Sets a specific value in the instance to the given value 
	 * (internal floating-point format). Performs a deep copy
	 * of the vector of attribute values before the value is set.
	 * Does exactly the same thing as setValue().
	 *
	 * @param indexOfIndex the index of the attribute's index 
	 * @param value the new attribute value (If the corresponding
	 * attribute is nominal (or a string) then this is the new value's
	 * index as a double).  
	 */
	public void setValueSparse(int indexOfIndex, double value) {

		freshAttributeVector();
		m_AttValues[indexOfIndex] = value;
	}

	/**
	 * Sets a value of a nominal or string attribute to the given
	 * value. Performs a deep copy of the vector of attribute values
	 * before the value is set.
	 *
	 * @param attIndex the attribute's index
	 * @param value the new attribute value (If the attribute
	 * is a string attribute and the value can't be found,
	 * the value is added to the attribute).
	 * @throws UnassignedDatasetException if the dataset is not set
	 * @throws IllegalArgumentException if the selected
	 * attribute is not nominal or a string, or the supplied value couldn't 
	 * be found for a nominal attribute 
	 */
	//@ requires m_Dataset != null;
	public final void setValue(int attIndex, String value) {
		Attribute a = Attributes.getAttribute(attIndex);
		int valIndex;

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		}
		if (!(a.getType()==Attribute.NOMINAL)) {
			throw new IllegalArgumentException("Attribute neither nominal nor string!");
		}
//		valIndex = attribute(attIndex).indexOfValue(value);
//		if (valIndex == -1) {
//			if (a.getType()==Attribute.NOMINAL) {
//				throw new IllegalArgumentException("Value not defined for given nominal attribute!");
//			} else {
//				attribute(attIndex).forceAddValue(value);
//				valIndex = attribute(attIndex).indexOfValue(value);
//			}
//		}
		valIndex = -1;
		for(int i=0;i<a.getNumNominalValues();i++)
			if(a.getNominalValue(i).compareTo(value)==0)
				valIndex = i;
		setValue(attIndex, (double)valIndex); 
	}

	/**
	 * Sets a specific value in the instance to the given value
	 * (internal floating-point format). Performs a deep copy of the
	 * vector of attribute values before the value is set, so if you are
	 * planning on calling setValue many times it may be faster to
	 * create a new instance using toDoubleArray.  The given attribute
	 * has to belong to a dataset.
	 *
	 * @param att the attribute 
	 * @param value the new attribute value (If the corresponding
	 * attribute is nominal (or a string) then this is the new value's
	 * index as a double).  
	 */
	public final void setValue(Attribute att, double value) {
		int index;
		index = -1;
		for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
			if(att == Attributes.getAttribute(index))
				index = i;
		setValue(index, value);
	}

	/**
	 * Sets a value of an nominal or string attribute to the given
	 * value. Performs a deep copy of the vector of attribute values
	 * before the value is set, so if you are planning on calling setValue many
	 * times it may be faster to create a new instance using toDoubleArray.
	 * The given attribute has to belong to a dataset.
	 *
	 * @param att the attribute
	 * @param value the new attribute value (If the attribute
	 * is a string attribute and the value can't be found,
	 * the value is added to the attribute).
	 * @throws IllegalArgumentException if the the attribute is not
	 * nominal or a string, or the value couldn't be found for a nominal
	 * attribute 
	 */
	public final void setValue(Attribute att, String value) {
		int index,valIndex;
		index = -1;
		for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
			if(att == Attributes.getAttribute(index))
				index = i;
		
		valIndex = -1;
		for(int i=0;i<att.getNumNominalValues();i++){
			if(att.getNominalValue(i).compareTo(value)==0)
				valIndex = i;
		}
		setValue(index, (double)valIndex);
	}

	/**
	 * Sets the weight of an instance.
	 *
	 * @param weight the weight
	 */
	public final void setWeight(double weight) {

		m_Weight = weight;
	}

	/** 
	 * Returns the relational value of a relational attribute.
	 *
	 * @param attIndex the attribute's index
	 * @return the corresponding relation as an Instances object
	 * @throws IllegalArgumentException if the attribute is not a
	 * relation-valued attribute
	 * @throws UnassignedDatasetException if the instance doesn't belong
	 * to a dataset.
	 */
	//@ requires m_Dataset != null;
//	public final /*@pure@*/ Instances relationalValue(int attIndex) {
//
//		if (m_Dataset == null) {
//			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
//		} 
//		return relationalValue(m_Dataset.attribute(attIndex));
//	}


	/** 
	 * Returns the relational value of a relational attribute.
	 *
	 * @param att the attribute
	 * @return the corresponding relation as an Instances object
	 * @throws IllegalArgumentException if the attribute is not a
	 * relation-valued attribute
	 * @throws UnassignedDatasetException if the instance doesn't belong
	 * to a dataset.
	 */
//	public final /*@pure@*/ Instances relationalValue(Attribute att) {
//
//		int attIndex = att.index();
//		if (att.isRelationValued()) {
//			return att.relation((int) value(attIndex));
//		} else {
//			throw new IllegalArgumentException("Attribute isn't relation-valued!");
//		}
//	}

	/** 
	 * Returns the value of a nominal, string, date, or relational attribute
	 * for the instance as a string.
	 *
	 * @param attIndex the attribute's index
	 * @return the value as a string
	 * @throws IllegalArgumentException if the attribute is not a nominal,
	 * string, date, or relation-valued attribute.
	 * @throws UnassignedDatasetException if the instance doesn't belong
	 * to a dataset.
	 */
	//@ requires m_Dataset != null;
	public final /*@pure@*/ String stringValue(int attIndex) {

		if (m_Dataset == null) {
			throw new UnassignedDatasetException("Instance doesn't have access to a dataset!");
		} 
		return stringValue(m_Dataset.attribute(attIndex));
	}


	/** 
	 * Returns the value of a nominal, string, date, or relational attribute
	 * for the instance as a string.
	 *
	 * @param att the attribute
	 * @return the value as a string
	 * @throws IllegalArgumentException if the attribute is not a nominal,
	 * string, date, or relation-valued attribute.
	 * @throws UnassignedDatasetException if the instance doesn't belong
	 * to a dataset.
	 */
	public final /*@pure@*/ String stringValue(Attribute att) {
		int index;
		Attribute a;
		index = -1;
		if(m_Dataset!=null){
			for(int i=0;i<m_Dataset.numAttributes() && index ==-1;i++){
				a = m_Dataset.attribute(i);
				if(att == a)
					index = i;
			}
		}else{
			for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
				if(att == Attributes.getAttribute(index))
					index = i;
		}
		int attIndex = index;
		switch (att.getType()) {
		case Attribute.NOMINAL:
			return att.getNominalValue((int) value(attIndex));
		default:
			throw new IllegalArgumentException("Attribute isn't nominal, string or date!");
		}
	}

	/**
	 * Returns the values of each attribute as an array of doubles.
	 *
	 * @return an array containing all the instance attribute values
	 */
	public double[] toDoubleArray() {

		double[] newValues = new double[m_AttValues.length];
		System.arraycopy(m_AttValues, 0, newValues, 0, 
				m_AttValues.length);
		return newValues;
	}

	/**
	 * Returns the description of one instance. If the instance
	 * doesn't have access to a dataset, it returns the internal
	 * floating-point values. Quotes string
	 * values that contain whitespace characters.
	 *
	 * @return the instance's description as a string
	 */
	public String toString() {

		StringBuffer text = new StringBuffer();

		for (int i = 0; i < m_AttValues.length; i++) {
			if (i > 0) text.append(",");
			text.append(toString(i));
		}

		return text.toString();
	}

	/**
	 * Returns the description of one value of the instance as a 
	 * string. If the instance doesn't have access to a dataset, it 
	 * returns the internal floating-point value. Quotes string
	 * values that contain whitespace characters, or if they
	 * are a question mark.
	 *
	 * @param attIndex the attribute's index
	 * @return the value's description as a string
	 */
	public final /*@pure@*/ String toString(int attIndex) {

		StringBuffer text = new StringBuffer();

		if (isMissing(attIndex)) {
			text.append("?");
		} else {
			if (m_Dataset == null) {
				text.append(Utils.doubleToString(m_AttValues[attIndex],6));
			} else {
				switch (m_Dataset.attribute(attIndex).getType()) {
				case Attribute.NOMINAL:
					text.append(Utils.quote(stringValue(attIndex)));
					break;
				case Attribute.INTEGER:
				case Attribute.REAL:
					text.append(Utils.doubleToString(value(attIndex),6));
					break;
				default:
					throw new IllegalStateException("Unknown attribute type");
				}
			}
		}
		return text.toString();
	}

	/**
	 * Returns the description of one value of the instance as a 
	 * string. If the instance doesn't have access to a dataset it 
	 * returns the internal floating-point value. Quotes string
	 * values that contain whitespace characters, or if they
	 * are a question mark.
	 * The given attribute has to belong to a dataset.
	 *
	 * @param att the attribute
	 * @return the value's description as a string
	 */
//	public final String toString(Attribute att) {
//
//		return toString(att.index());
//	}

	/**
	 * Returns an instance's attribute value in internal format.
	 *
	 * @param attIndex the attribute's index
	 * @return the specified value as a double (If the corresponding
	 * attribute is nominal (or a string) then it returns the value's index as a 
	 * double).
	 */
	public /*@pure@*/ double value(int attIndex) {

		return m_AttValues[attIndex];
	}

	/**
	 * Returns an instance's attribute value in internal format.
	 * Does exactly the same thing as value() if applied to an Instance.
	 *
	 * @param indexOfIndex the index of the attribute's index
	 * @return the specified value as a double (If the corresponding
	 * attribute is nominal (or a string) then it returns the value's index as a 
	 * double).
	 */
	public /*@pure@*/ double valueSparse(int indexOfIndex) {

		return m_AttValues[indexOfIndex];
	}  

	/**
	 * Returns an instance's attribute value in internal format.
	 * The given attribute has to belong to a dataset.
	 *
	 * @param att the attribute
	 * @return the specified value as a double (If the corresponding
	 * attribute is nominal (or a string) then it returns the value's index as a
	 * double).
	 */
	public /*@pure@*/ double value(Attribute att) {
		int index;
		index = -1;
		for(int i=0;i<Attributes.getNumAttributes() && index ==-1;i++)
			if(att == Attributes.getAttribute(index))
				index = i;
		return value(index);
	}

	/**
	 * Returns the instance's weight.
	 *
	 * @return the instance's weight as a double
	 */
	public final /*@pure@*/ double weight() {

		return m_Weight;
	}

	/**
	 * Deletes an attribute at the given position (0 to 
	 * numAttributes() - 1).
	 *
	 * @param position the attribute's position
	 */
	void forceDeleteAttributeAt(int position) {

		double[] newValues = new double[m_AttValues.length - 1];

		System.arraycopy(m_AttValues, 0, newValues, 0, position);
		if (position < m_AttValues.length - 1) {
			System.arraycopy(m_AttValues, position + 1, 
					newValues, position, 
					m_AttValues.length - (position + 1));
		}
		m_AttValues = newValues;
	}

	/**
	 * Inserts an attribute at the given position
	 * (0 to numAttributes()) and sets its value to be missing. 
	 *
	 * @param position the attribute's position
	 */
	void forceInsertAttributeAt(int position)  {

		double[] newValues = new double[m_AttValues.length + 1];

		System.arraycopy(m_AttValues, 0, newValues, 0, position);
		newValues[position] = MISSING_VALUE;
		System.arraycopy(m_AttValues, position, newValues, 
				position + 1, m_AttValues.length - position);
		m_AttValues = newValues;
	}

	/**
	 * Private constructor for subclasses. Does nothing.
	 */
	protected Instance() {
	}

	/**
	 * Clones the attribute vector of the instance and
	 * overwrites it with the clone.
	 */
	private void freshAttributeVector() {

		m_AttValues = toDoubleArray();
	}

	/**
	 * Main method for testing this class.
	 * 
	 * @param options the commandline options - ignored
	 */
	//@ requires options != null;
//	public static void main(String[] options) {
//
//		try {
//
//			// Create numeric attributes "length" and "weight"
//			Attribute length = new Attribute("length");
//			Attribute weight = new Attribute("weight");
//
//			// Create vector to hold nominal values "first", "second", "third" 
//			FastVector my_nominal_values = new FastVector(3); 
//			my_nominal_values.addElement("first"); 
//			my_nominal_values.addElement("second"); 
//			my_nominal_values.addElement("third"); 
//
//			// Create nominal attribute "position" 
//			Attribute position = new Attribute("position", my_nominal_values);
//
//			// Create vector of the above attributes 
//			FastVector attributes = new FastVector(3);
//			attributes.addElement(length);
//			attributes.addElement(weight);
//			attributes.addElement(position);
//
//			// Create the empty dataset "race" with above attributes
//			Instances race = new Instances("race", attributes, 0);
//
//			// Make position the class attribute
//			race.setClassIndex(position.index());
//
//			// Create empty instance with three attribute values
//			Instance inst = new Instance(3);
//
//			// Set instance's values for the attributes "length", "weight", and "position"
//			inst.setValue(length, 5.3);
//			inst.setValue(weight, 300);
//			inst.setValue(position, "first");
//
//			// Set instance's dataset to be the dataset "race"
//			inst.setDataset(race);
//
//			// Print the instance
//			System.out.println("The instance: " + inst);
//
//			// Print the first attribute
//			System.out.println("First attribute: " + inst.attribute(0));
//
//			// Print the class attribute
//			System.out.println("Class attribute: " + inst.classAttribute());
//
//			// Print the class index
//			System.out.println("Class index: " + inst.classIndex());
//
//			// Say if class is missing
//			System.out.println("Class is missing: " + inst.classIsMissing());
//
//			// Print the instance's class value in internal format
//			System.out.println("Class value (internal format): " + inst.classValue());
//
//			// Print a shallow copy of this instance
//			Instance copy = (Instance) inst.copy();
//			System.out.println("Shallow copy: " + copy);
//
//			// Set dataset for shallow copy
//			copy.setDataset(inst.dataset());
//			System.out.println("Shallow copy with dataset set: " + copy);
//
//			// Unset dataset for copy, delete first attribute, and insert it again
//			copy.setDataset(null);
//			copy.deleteAttributeAt(0);
//			copy.insertAttributeAt(0);
//			copy.setDataset(inst.dataset());
//			System.out.println("Copy with first attribute deleted and inserted: " + copy); 
//
//			// Enumerate attributes (leaving out the class attribute)
//			System.out.println("Enumerating attributes (leaving out class):");
//			Enumeration enu = inst.enumerateAttributes();
//			while (enu.hasMoreElements()) {
//				Attribute att = (Attribute) enu.nextElement();
//				System.out.println(att);
//			}
//
//			// Headers are equivalent?
//			System.out.println("Header of original and copy equivalent: " +
//					inst.equalHeaders(copy));
//
//			// Test for missing values
//			System.out.println("Length of copy missing: " + copy.isMissing(length));
//			System.out.println("Weight of copy missing: " + copy.isMissing(weight.index()));
//			System.out.println("Length of copy missing: " + 
//					Instance.isMissingValue(copy.value(length)));
//			System.out.println("Missing value coded as: " + Instance.missingValue());
//
//			// Prints number of attributes and classes
//			System.out.println("Number of attributes: " + copy.numAttributes());
//			System.out.println("Number of classes: " + copy.numClasses());
//
//			// Replace missing values
//			double[] meansAndModes = {2, 3, 0};
//			copy.replaceMissingValues(meansAndModes);
//			System.out.println("Copy with missing value replaced: " + copy);
//
//			// Setting and getting values and weights
//			copy.setClassMissing();
//			System.out.println("Copy with missing class: " + copy);
//			copy.setClassValue(0);
//			System.out.println("Copy with class value set to first value: " + copy);
//			copy.setClassValue("third");
//			System.out.println("Copy with class value set to \"third\": " + copy);
//			copy.setMissing(1);
//			System.out.println("Copy with second attribute set to be missing: " + copy);
//			copy.setMissing(length);
//			System.out.println("Copy with length set to be missing: " + copy);
//			copy.setValue(0, 0);
//			System.out.println("Copy with first attribute set to 0: " + copy);
//			copy.setValue(weight, 1);
//			System.out.println("Copy with weight attribute set to 1: " + copy);
//			copy.setValue(position, "second");
//			System.out.println("Copy with position set to \"second\": " + copy);
//			copy.setValue(2, "first");
//			System.out.println("Copy with last attribute set to \"first\": " + copy);
//			System.out.println("Current weight of instance copy: " + copy.weight());
//			copy.setWeight(2);
//			System.out.println("Current weight of instance copy (set to 2): " + copy.weight());
//			System.out.println("Last value of copy: " + copy.toString(2));
//			System.out.println("Value of position for copy: " + copy.toString(position));
//			System.out.println("Last value of copy (internal format): " + copy.value(2));
//			System.out.println("Value of position for copy (internal format): " + 
//					copy.value(position));
//		} catch (Exception e) {
//			e.printStackTrace();
//		}
//	}
}

	
